1. Field of the Invention
The present invention concerns a method and a device for adjusting the transverse position of at least part of a moving machine moving along a predetermined path across a terrain in order to construct a structure on said terrain.
In the context of the present invention the expression "transverse position of a moving machine or part of a moving machine" refers to the position of said machine or said part thereof in the plane transverse to the movement of the machine.
The present invention applies more particularly, although not exclusively, to adjusting the transverse position of moving machines used on civil engineering sites to construct structures. In the context of the present invention, the term "structure" means any form of construction that can be effected on a terrain; by transformation of the terrain or otherwise, for example surfacing a road or an airport runway or digging a trench.
2. Description of the Prior Art
The machines used to carry out this work must usually be directed along a predefined path in a geodesic frame of reference. To construct said structure according to a predefined design, said machine or at least a part of said machine, generally the part of said machine designed to construct the structure, must be in an appropriate transverse position as the machine moves.
The path to be followed is generally marked out by a line stretched between a large number of stakes fixed into the ground and the machine is provided with mechanical feelers that remain in contact with said line at all times and which signal any variation of the position of the machine relative to the prescribed position indicated by said line, enabling adjustment of the transverse position of the machine by controlling it in such manner as to eliminate any variation in position that may appear.
Said line at a particular height above the ground and running along a particular path enables the machine to follow said particular path and enables adjustment of the transverse position of the machine as it moves.
This method of adjusting the transverse position has many drawbacks, and in particular:
a high operating cost due to the installation of the line and the stakes carrying said line; PA0 the impediment that said line stretched above the ground represents; and PA0 the impossibility of having the machine take up a transverse position different from that defined by the stretched line. PA0 A/ a theoretical transverse position of said part of the machine is determined; and PA0 B/ during said displacement along said particular path, the transverse position of said part of the machine is adjusted by carrying out the following operations repetitively: PA0 a) the profile of said terrain is remotely sensed; PA0 b) the required theoretical transverse position of said part of the machine during the construction of said structure as said machine moves along said particular path is determined on the basis of the structure to be constructed and the sensed profile. PA0 a) a point whose coordinates are known in said frame of reference is defined as a reference point; PA0 b) the distance D between said measurement point and said reference point is determined; PA0 c) the angle .phi. between the vertical and a straight line segment passing through said measurement point and said reference point is determined; PA0 d) the angle .alpha. between a particular horizontal direction, the coordinates of which are known in said frame of reference, and the projection into the horizontal plane of said straight line segment passing through said measurement point and said reference point is determined; and PA0 e) the coordinates of the measurement point in said frame of reference are determined from the coordinates of said reference point, from said distance D and from said angles 100 and .alpha.. PA0 a measuring device for carrying out measurements for determining the coordinates of the measurement points of the terrain; PA0 at least one sensor adapted for carrying out measurements for determining the actual transverse position of said part of the machine; PA0 positioning means for transversely positioning said part of said machine; and PA0 a computer connected to said measuring device, to said sensor and to said positioning means for:
French patent FR-A-2 637 625 describes a method for adjusting the transverse position of at least part of a mobile machine adapted to construct a structure in a terrain and to this end moving over said terrain along a particular path, in which method:
the actual transverse position of said part of the machine is detected; and PA1 said part of the machine is commanded so that its actual transverse position corresponds to the particular theoretical transverse position. PA1 determining the theoretical transverse position of said part of the machine; PA1 determining the actual transverse position of said part of the machine; and PA1 controlling the positioning means so that the actual transverse position of said part of the machine is made to correspond to the theoretical transverse position as the machine moves. PA1 a laser source adapted to emit a laser beam; and PA1 a video camera for detecting the laser beam emitted by said laser source and reflected by said materialization member and for determining accordingly the actual transverse position of said part of the machine.
An object of the present invention is to improve on the above method and the present invention concerns a method and a device for adjusting the transverse position of at least one part of a mobile machine that does not require for its implementation any mechanical contact with a line or with any other control means fixed to the ground and liable to constitute an impediment.
Document GB-2 228 507 describes control equipment for an earthmoving machine and including a laser emitter at a fixed point on the ground and emitting a laser beam that can be detected by sensors installed on the machine, said laser beam defining an imaginary fixed line determining the path to be followed by the machine and serving as a reference for control of an earthmoving unit of said machine in a plane transverse to said imaginary line.
The method proposed by the above document has a number of major drawbacks, however. Firstly, a laser emitter at a fixed point is required, which can obviously cause problems in bad weather conditions, all the more so since an emitter of this kind is usually constructed from relatively fragile components.
Secondly, the adjustment of the transverse position is not effected relative to the ground, but relative to the imaginary line defined by said laser beam. This is not a problem in the case of the earthmoving application with which the aforementioned document is concerned, but this method of adjustment may be difficult to use to construct a structure having a particular shape dependent on the profile of the terrain, since the shape of the terrain is not known in this case. On civil engineering sites in particular, many structures are constructed and other works are carried out in accordance with the profile of the terrain concerned, and this rules out the use of the solution disclosed in document GB-2 228 507.
Another object of the invention is to solve these drawbacks. It concerns a method for adjusting the transverse position of at least one part of a mobile machine adapted to move over a terrain to construct a structure, the implementation of this adjustment not requiring any contact with elements on the ground but nevertheless allowing for the shape of the terrain.